Multi-wavelength semiconductor lasers

Abstract

A multi-wavelength semiconductor laser is formed by monolithically integrating a plurality of laser diodes (1, 2) with at least one isolator section (3) and a coupler (4), which couples the different emission wavelengths λ1, λ2 into one output port (5). The isolator section can be either a light absorptive type or wavelength selective type, including a Bragg grating type isolator or a photonic bandgap crystal type isolator. The coupler is preferably a Y-junction coupler, but can also be a multi-branch waveguide coupler or a waveguide directional coupler.

Description

FIELD OF THE INVENTION[0001]The present invention pertains to the field of semiconductor laser fabrication and in particular to a method for manufacturing integrated single output multiple wavelength lasers and related photonic integrated devices to be utilized in wavelength division multiplexing (WDM) optical communication system, optical recording and measurementBACKGROUND OF THE INVENTION[0002]Multi-wavelength laser sources are key elements for a variety of applications such as wavelength division multiplexing (WDM), optical recording, color displays and optical color printing. Several methods have been proposed and patented for the realization of these multi-wavelength laser sources and the integration with modulators, as can be seen in U.S. Pat. No. 4,955,030 (Menigaux), U.S. Pat. No. 4,831,629 (Paoli), U.S. Pat. No. 4,993,036 (Ikeda), U.S. Pat. No. 5,384,797 (Welch), U.S. Pat. No. 5,519,721 (Takano). They can be realized by the non-uniform current pumping resulting in areas wi...

AI Technical Summary

Benefits of technology

[0005]The invention has as its objective, to introduce an isolator or isolators monolithically integrated with the semiconductor laser arrays and to provide an easy method of producing integrated multiple wavelength semiconductor lasers that can independently emit each wavelength in one spot.

[0011]The isolator section may be, for example, either a wavelength selective type or a light absorptive type. For the first type, it can be a distributed Bragg grating type isolator or a photonic bandgap crystal type isolator which is transmissive to one wavelength of the laser diode section but highly reflective to other wavelengths. For a dual wavelength laser source comprising two laser diode sections, an isolator may be integrated with one or each of laser diode sections and tuned to reflect the other wavelength which is not desired. For the second type of isolation, the isolator has a band gap energy transparent to the laser wavelength of the laser diode section but absorbing to all other laser wavelengths. There is no need for an electrical contact for the isolation region thus giving rise to ease of fabrication and operation.

Problems solved by technology

However, many of the multiple wavelength laser sources or arrays fabricated rely on a large spatial separation between different wavelength elements, and therefore complex focusing optics are required to align the individual lasers to the optical fiber.

An inevitable drawback of this method is that there cannot be many wavelengths integrated together otherwise the device will be too long and the internal loss will be large.

One problem arising from the combination of different wavelengths together is that the cross talks among these wavelengths are inevitable without additional treatment.

This method is a little complicated since it needs a lot of additional electrodes to control each modulator.

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